I. Field
The present disclosure relates to communication systems and to techniques for preventing the collision of physical cell identifiers (e.g., primary scrambling codes).
II. Background
Wireless communication networks are widely deployed to provide various communication content such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless communication network may include a number of base stations that can support communication for a number of mobile entities, such as, for example, user equipments (UEs). A UE may communicate with a base station via the downlink (DL) and uplink (UL). The DL (or forward link) refers to the communication link from the base station to the UE, and the UL (or reverse link) refers to the communication link from the UE to the base station.
The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) represents a major advance in cellular technology as an evolution of Global System for Mobile communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE physical layer (PHY) provides a highly efficient way to convey both data and control information between base stations, such as an evolved Node Bs (eNBs), and mobile entities, such as UEs.
In recent years, users have started to replace fixed line broadband communications with mobile broadband communications and have increasingly demanded great voice quality, reliable service, and low prices, especially at their home or office locations. In order to provide indoor services, network operators may deploy different solutions. For networks with moderate traffic, operators may rely on macro cellular base stations to transmit the signal into buildings. However, in areas where building penetration loss is high, it may be difficult to maintain acceptable signal quality, and thus other solutions are desired. New solutions are frequently desired to make the best of the limited radio resources such as space and spectrum. Some of these solutions include intelligent repeaters, remote radio heads, and small-coverage base stations (e.g., picocells and femtocells).
The Femto Forum, a non-profit membership organization focused on standardization and promotion of femtocell solutions, defines femto access points (FAPs), also referred to as femtocell units, to be low-powered wireless access points that operate in licensed spectrum and are controlled by the network operator, can be connected with existing handsets, and use a residential digital subscriber line (DSL) or cable connection for backhaul. In various standards or contexts, a FAP may be referred to as a home node B (HNB), home e-node B (HeNB), access point base station, etc. A femtocell may be referred to as a small cell herein.
As more small-coverage base stations are utilized to deploy more small cells, situations may arise where two or more neighboring small cells may have the same physical cell identifiers (e.g., primary scrambling codes), resulting in the collision of such physical cell identifiers. Accordingly, there is a need for a technique to detect and prevent such collisions, particularly in the context of densely deployed small cells.